Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

657
FXUS63 KLOT 162056
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
256 PM CST Fri Jan 16 2026

.KEY MESSAGES...

- Two clipper systems will bring a chance for accumulating snow
  with minor impacts during the afternoon and early evening
  hours of both Saturday and Sunday.

- Bitterly cold conditions are expected Sunday night through
  Tuesday morning with wind chills 15 below to 25 below zero
  possible Monday morning.

&&

.DISCUSSION...
Issued at 253 PM CST Fri Jan 16 2026

Periods of snow from multiple disturbances in overall northwest
flow will be the main story through early next week, with
increasingly colder conditions behind each system. While snow
showers will be possible at any time through at least Sunday
night, the potential for accumulating snow with minor impacts
will be confined to the mid afternoon to early evening each day.

Snow shower activity is currently at a lull early this
afternoon in the wake of this morning`s trough. Low-level warm
advection and some breaks in clouds have pushed temps well into
the 30s and wetbulb temps above freezing. Meanwhile, gradual CAA
aloft will weaken an existing inversion and deepen the surface-
based layer of steeper lapse rates. The combination of moisture
advection into the southwest CWA and a sheared-out remnant mid-
level trough has recently interacted with diurnal influences to
generate convective showers over west-central Illinois. Given
their convective nature, precip type should fall as all snow
with the heaviest cores, but lighter showers may exhibit a mix
of rain and snow over the next few hours south of the I-80
corridor. Sharp reductions in visibility can be expected with a
quick slushy accumulations of a few tenths of an inch possible
in the heaviest showers.

Farther north and west, a more prominent mid-level wave will
drift southeastward tonight. Modest low-level moisture with some
diurnal enhancement has supported the development of weaker
snow showers as far east as the Mississippi River north of the
Quad Cities. These showers should increase in coverage through
early evening, resulting in scattered to numerous showers across
northern Illinois very late this afternoon and into the
evening. Lastly, a cold front over eastern Iowa will provide
additional support for shower intensity and coverage this
evening. Marginal low-level temps ahead of the front should
limit overall impacts early this evening, but isolated bursts of
snow, especially on the cold front, may produce narrow swaths
of up to one inch of accumulation, winds gusting to 30 mph, and
falling temps. Not expecting these showers to meet snow squall
criteria (mainly due to temps near/above freezing), but will
need to monitor upstream trends for more impactful showers if
coverage/intensity increase more than expected or temps begin to
fall earlier.

The wave to the northwest will drift across Illinois through
the day Saturday and into the evening. With remaining mid-level
moisture, existing forcing, and relatively cold temps aloft, we
should see an associated band of light snow (up to one inch)
gradually shift southeastward across the CWA late morning into
early evening.

CAA will be minimal across the area Saturday night as low-level
flow quickly backs southwest ahead of a stronger trough over
the Upper Mississippi River Valley on Sunday. Guidance has
trended stronger and slightly farther south with this trough,
which, when paired with a 110-120 knot jet axis pointing ESE
into southern Illinois, has resulted in better forcing and top-
down saturation over northern Illinois and northwest Indiana
during the afternoon. The latest forecast of up to one inch is
supported by a vast majority of ensemble members with only a few
outliers with over one inch.

Expect daytime highs this weekend to settle in the mid to upper
teens amid gusty WNW to WSW winds, resulting in wind chills
topping out only just above zero. A next push of arctic air will
arrive late Sunday afternoon and evening, with notably colder
conditions Sunday night into Tuesday. Minimum wind chills Monday
morning are expected to be -20 to -25 degrees, with the
potential that a Cold Weather Advisory (-25 degrees) is needed
for at least some of the area. With the cold start to the day,
highs Monday will struggle to reach 10 degrees, with maximum
wind chills remaining solidly below zero. Winds will begin to
diminish Monday night as a surface high passes south of the
area, but wind chills as low as -15 degrees can be expected
Tuesday morning.

Beyond Tuesday, strong baroclinicity developing across the
central CONUS will support a more active period of weather over
or near our area as early as Tuesday night. Still a lot of
discrepancies in the broader model/ensemble systems chiefly due
to uncertainty as to where the baroclinic zone resides with
respect to out area.

Kluber

&&

.AVIATION /18Z TAFS THROUGH 00Z SUNDAY/...
Issued at 1123 AM CST Fri Jan 16 2026

A cooling low-level temperature profile atop the warming
boundary layer ahead of a 700mb vort/speed wave will promote
the redevelopment of snow showers across the airspace this
afternoon. With the convective layer forecasted to extend as
high as minus 15C, the most vigorous showers may be capable of
producing graupel (soft hail), westerly wind gusts in excess of
30 kt, and even a lightning strike. So, will maintain the
inherited TEMPO groups focusing on the late afternoon/early
evening time period (generally 22-02Z) for brief but stark
visibility reductions (1 mile or less) in snow.

Coverage of snow showers should taper prior to midnight.
Attention then turns toward an upper-level wave embedded within
broad upper-level cyclonic flow due to swing over the airspace
tomorrow. Am noting an increasing signal for the core of the
wave to pass directly over the airspace during the afternoon
hours (near or just after the end of the 24 hour TAF window for
most sites). With a continued cold temperature profile with a
deep layer of saturation within a low-centroid DGZ, am growing
increasingly concerned for the development of widespread and steady
fluffy snow across the airspace with prevailing LIFR to IFR
visibility. Will go ahead and introduce P6SM -SN (for flurries)
as early as daybreak at all terminals, and then 3SM -SN toward
the end of the 24 to 30-hour TAF window for RFD/ORD/MDW. If such
a signal continues going forward, lower visibility (1 to 2
miles, if not periodically 1/2 to 3/4SM) will need to be
introduced into the TAFs.

Winds will remain westerly and periods of MVFR cigs will
prevail through much of the TAF period.

Borchardt

&&

.HYDROLOGY...
Issued at 253 PM CST Fri Jan 16 2026

The upcoming extended period of very cold temperatures will likely
result in the rapid development of ice on area rivers and streams
which may increase the chance of localized ice jam flooding. Last
week`s heavy rainfall has resulted in increased streamflow in
several basins, including the Fox, Des Plains, and Illinois River
basins. This higher streamflow will result in a greater potential
for freeze up ice jam flooding.

- Izzi

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 3 AM CST Saturday for Winthrop
     Harbor IL to Gary IN.

     Small Craft Advisory until 3 AM CST Sunday for Gary to Burns
     Harbor IN-Burns Harbor to Michigan City IN.

&&

$$

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